Leaving us hanging on this for 5 days was a bad move. Not only is it viewed as bad customer service, but it's just bad business. You guys need to start getting out in front of issues like this. Be proactive, not reactive.
It probably would have also been smart to more carefully scrutinize the code that calculates repair costs. It honestly sounds like one person's dumb mistake caused this whole mess.
You ultimately made the right decision on how to handle this. Now let's see how you implement it. If I were you, I'd post frequent warnings that repair costs will be going back up at the end of the 50% discount. I would also strongly consider phasing out the discount slowly. Raise it by 10 percentage points per week leading up to RotHC, for example. Players will be able to get used to the new costs and every week prices rise, it means we are one week closer to the expansion.